Our View: Monarchs and milkweed — Nature's balance again off kilter

Thursday

Mar 20, 2014 at 12:01 AM

The monarch butterfly was once a vivid sign that summer had arrived. The bright orange-and-black-winged insect flitted from flower to flower, brightening the day of virtually everyone who encountered it.

The monarch butterfly was once a vivid sign that summer had arrived. The bright orange-and-black-winged insect flitted from flower to flower, brightening the day of virtually everyone who encountered it.

The monarch's days, however, seem numbered. Their population has dwindled from billions to millions in the span of a decade, a sign that something is terribly wrong in the world of nature.

Despite its diminutive size, the monarch is a powerhouse of an insect. The adult insect can travel upwards of 2,500 miles from Canada to Mexico, with some making a 1,000-mile return trip back into the United States before laying eggs and dying.

Although there is no argument about the monarch's diminishing numbers, the cause of the decline is less than clear. Some have pointed to decimating ice storms and droughts, while others have focused on widespread logging in Mexico. Although there may be multiple contributing factors, many scientists point to the extensive die-off of milkweed, a staple of the monarch's diet.

The nationwide eradication of milkweed can in turn be traced back to the use of corporate chemical behemoth Monsanto's Roundup and similar herbicides using a chemical called glyphosate. They are ruthlessly effective in destroying plants that are not genetically manipulated to resist them, including milkweed. It is a nuisance to farmers, but butterfly gardeners well know the sweet, permeating aroma of milkweed when it flowers in summer, transforming a walk in the yard on a still July afternoon into heavenly reverie.

The same 10-year period that has witnessed an 81 percent decrease in the monarch population in the Midwest has coincided with a 58 percent reduction in the amount of milkweed nationwide. That same period has also seen a nearly tenfold increase in the use of glyphosate, jumping from 18.7 million pounds in 1993 to 182 million pounds today.

Monsanto claims the butterfly's numbers fluctuate dramatically from year to year, and that glyphosate is far from the only challenge the monarch faces. The company has even pledged to restore milkweed habitats, although it has offered no specific proposals thus far.

Monsanto is likely correct that glyphosate is not the only issue here. Illegal logging and the expansion of various cash crops have contributed to the monarch's problems. In addition, some of the butterfly's loudest advocates have acknowledged that there is little likelihood that any effort to secure an outright ban on glyphosate would be successful.

Although it is difficult to prove a causal relationship between glyphosate and the monarch's population problems, it is difficult to look at the numbers and not see more than a correlation of the data.

The fact is monarchs are disappearing at a rapid rate and to merely shrug our shoulders and hope they will rebound on their own seems like a disingenuous effort to alleviate our likely responsibility. Further, if we can acknowledge that glyphosate plays at least some role in the monarch's population woes, what other, less visible impacts may it be having as well?

Nothing happens in a vacuum when it comes to nature; everything is interconnected in ways that sometimes take years or decades to be revealed. The monarch may be an isolated case, an aberration that showcases a unique impact of this particular chemical. Or, it may be sending us a warning that we would do well to heed.